Electric furnace



J. THOMSON.

necmq FURNACE. APPLICATION FILED NOV- 19, I919.

Patenrbd Sept. 7, 1920.

5 SHEETS-SHEET 3. IHOMSON. Eucmc rumucs.

APPLICATION FILED NOV. 1!. "l9.

Pam tedse t. 7,1920.

5 SHEEN-SHEET 2" 1. THOMSON.

ELECTRIC FURNACE.

APPLICATION FILED NOV. 19, I9l9 1,351,977. Pawnwdfiept. 7, 1920.

Elma/Mm 3&3 alien W130 J. THOMSON.

ELECTRIC FURNACE.

APPLICATION FILED nov. 19, 1919.

1,351,977. PatenfodSept. 7,1920.

5 SNEETS SHEET 4.

J. THOMSON.

ELECTRIC FURNACE.

APPLICATION FILED NOV. 19, 1919.

Patented Sept. 7, 1920.

5 SHEETSSHEET 5.

anvem to z UNITED STATES JOHN THOMSON, 01E BB-ODKL'YH, It"

PATENT OFFICE.-

EEJEGTRIC FURIQAGZEL Application filed To all whom may, concern it known that 1, Joan Tr-rontson, a iizen of the United States, and a resi- -'nt of borough of Brooklyn, county of .ings, State of New Yorlr, have invented few and useful improvements in Electric urnaces, of which the following is a specior si les, of a receptacle for containing the material to be heated that essentially all of the heat-rav- 4 ardly radiated therefrom v ctional cover, capable of removed from the furnace the =, contiguous vertical suriace of the a unit, in singular, is formed by two monolithic carbon limbs, one pair of ends having hitherto been joined to operate in series, by

' a carbon connector, wholly contained with- Sneeification of Letters Patent.

"in no,

Patented Sept. 7, 1920.

Serial No. 339,119.

in the furnace-chamber, the alternate ends being connected to carbon terminals which pass out through a wall, or walls, of the rurnace,

In the present case the monolithic limbs U, of the resistor are detachably con nected to carbon terminals D, E, and F, G, {see F l) which pass out from the furnace-chamber H through opposite sidewalls of the rnace. in this wise, either of the limbs may be operated as a distinct elementalresistor, or both may be operated in parallel; but by joining a pair of the terminals, as E, G, with a copper connector I, on the exterior of the furnace, the two limbs are operative in series. Hence, if it should become desirable, for any reason, to change from parallel this can be effected by simply disconnecting the connector; or,

o e or the other of the limbs fail,

to limb be operated as an 111- tegral unit, whereby a partially fused charge can be fiuidified instead of being noted by'J, and rest upon refractory bases l l Figs. 2 and transversely center of e furnace-chamthe drawings, e angles of these are about 30 which, however, may be ordinating condition be realized.

The monolithic limbs of the resistor are here show n as being embedded, or covered, with granular carbon L which may be more or less consumed if air is present but serves to prevent the oxidization of the resistor itself. Between the granular carbon and the monolithic resistor, there may be a layer of material M {see Fig. 5) relatively non-conductive to electricity. Consequently, heat is developed solely by the monolithic resistor; is transferred by conduction to the broken carbon and is then radiated in parallel rays vertical to the emittin surface, as indicated by the arrows a, I). he heat thus radiated is then refracted by the inner surface N of the cover in correspondingly parallel rays, as is indicated by the arrows d, 0, and impinge upon the surface of the bath or object to be heated. To express the problem in concrete terms, the requisite condiwnwardly the horizontal, v

esser or greater, 5 ending upon the $57 (and! tions, whereby to realize the foregoing desirable sheet, are that the relatively flat heat-emitting face of the resistor or of the granular carbon, and the flat heat-refracting face of the cover shall be disposed at such a relative angle as will throw the heat-rays in parallel. to the desired surface of impact.

it follows, therefore, that the area of the heat-emitting surface acted upon by the resistor may be equal to, or lesser than, or greater than, the heat-absorbing surface of the charge; also that the deflection of the radiated heat-rays may be controllably realized by disposing the resistor along a horizontal plane and obtaining the desired defleeting an le from the cover, as is illustrated in Fig. 6, in which the resistor-limbs r are laid horizontally while the roof is sloped upwardly from the horizontal, right and left, toward the center. The roof-angles here shown are about 25. Moreover, in this illustration the heat-emitting surface is shown as having about twice the area of the bath, whence the parallel heat-rays-from each limb of the resistor have approximately common points of impin ement. Obviously, in a case where it is desirable to deliver the greatest possible volume of heat at a given temperature this realization of the invention would be the better.

It will now be perceived that approximately every portion of the entire surface of the bath, J, is subjected to refracted heat-units traversing nearly uniform distances; and that the dynamic eflect thereof will only be so much less than that of the radiated heat a, b as is measurable by the energy necessary to cause the downward'defiection. The practical advantages of the foregoing are the avoidance of hot-spots at, or in, any portion of the bath or article to be heated; consequently the potential difference of temperature between the source and the delivery is uniformly distributed and heat-units may be supplied as rapidly as they can be absorbed.

When the conditions are such that oxidization will not ensue, a monolithic zig-zag carbon resistor may be used without being embedded in crushed carbon.

I have previously disclosed how controlled heat-refractions from portions of a monolithic resistor may be realized from the sidewalls of electric furnaces as, for example, in my But if a monolithic resistor is disposed,

as shown in the drawings, and enveloping Patents No. 1,308,877 and No. 1,308,880 of July 8,1919.

Incidentally, an arched cover would not so effectively meet the desired thermal con ditions herein set forth, in that the heat rays refracted therefrom would be converged toward. its center; moreover, there would then be a more considerable difference in the lineal distances traversed by the heat-rays refracted from the arch to the charge; the cubical capacity of the furnacechamber would need be greater and re moval of the entire cover would then be required in order to reach the resistor. @n the other hand, the construction of a flat cover for furnaces of large capacity present considerable difliculties in that monolithic refractories which will enduringly span wide chambers, when subjected to high temperatures, are limited and expensive. This problem has been successfully solved, by the employment of ordinary tiles or bricks in the following manner:

The cover or roof, in singular, is prefersistor can be removed and replaced. The

tiles or bricks are pierced as r (see Fig. 2) assembled to produce a section and upon the top thereof is a layer of heat-insulating blocks. through the tile-holes and corresponding pipes, or in this place solid rods, overlie the said insulating blocks. Tron clamps, as P, are engaged by the pipes whose ends are threaded and the structure is then very firmly bound together by nuts, as 25. Each pair of pipes, or a pipe and a rod, one being superimposed above the other, form a very strong and rigid structure, analogous to a bridge-member; consequently the sections may be swung ofl' without liability of deformation. llf the pipes become so highly heated as to produce plasticity, this can be corrected b circulating therethrough air or water. bviously a so-called.flat arch could be employed but it also would usually Iron pipes, V, are. introduced' inner surface is not exlposed to atmosphere.

The char ing port,

, is normally closed by a door, S, formed of suitable refractory material, in the top of which is a hook, as v, to which a chain may be attached (not shown) passing upwardly over a pulley and thence downwardly, whereby the said door can be elevated, as shown in Fig. 1, or lowered, as shown in Fig. 3. This door is freely fitted within a gap or recess T so that its inner surface is brought approximately parallel with the contiguous, inner vertical surface of the chamber wall. Ilence a pernicious heat-absorbing pocket, which would exist if the door were disposed outwardly, is avoided; also, when elevated, its hot, inner surface slides upwardly in contact with heated brickwork, instead of, as is usually the case, being exposed to a cold surface and atmosphere. Incidentally, this disposal and mode of operation is very convenient in that the open door. is not in the way of an operator and the maximum of accessibility to the port and the furnace-chamber is afforded. i

Obviously various changes may be made in the details of construction and arrange- I ment of ports herein illustrated and tion.

What I claim is: 1. An electric furnace limb being connected to carbon terminals which pass out from the heating chamber to Y the exterior of the furnace, andya metallic connector, outside of the furnace-chamber, attached to one terminal of each of said air of terminals, whereby the limbs of sai resistor may be velectrically incited to' series.

2. An electric furnace provided. with a compound, monolithic, zig-zag, carbon resistor formed of two limbs, the ends of each limb being connected to carbon terminals which pass out from the heating chamber to the exterior of the furnace, whereby the said terminals may be so connected, outside of the furnace-chamber, as to electrically incite both of said limbs in parallel or either thereof in series.

3. An electric furnace provided with a compound zig-zag carbon resistor 'whose limbs are disposed along the o posing sides .of a charge-receptacle, said lim s being connected to suitableterminals, and an overlying cover for-the furnace from which the heat-rays upwardly radiated in parallel by scribed, within the purview of this'inven terminals, disposed along the side of a charge-receptacle, said resistor being set at an angle, transversely, and an over-lying rays radiated from the resistor in parallel are refracted in parallel from the cover to the object to be heated.

5. An electric furnace provided with a zig-zag carbon resistor, connected to suitable terminals disposed along the side of a charge-receptacle, said resistor being, set horizontally and an overlying cover for the furnace having a'flat surface set at an angle transversely from the horizontal, whereby the heat-rays radiated from the resistor in parallel are refracted from the cover in parallel to the object to be heated. n

6. An electric furnace provided with a monolithic zig-zag carbonresistor connected to suitable'terminals disposed along the side, orsides, of a charge-receptacle, said resistor beingembedded in or-covered 'by crushed provided with acompound, monolithic, zig-zag, carbon resistor formed of two limbs, the ends of each carbon, and an over-lying sectional roof. for the furnace whose arrangement and construction are such that one or more of its sections may-be partially slid off side-wise from the furnace-chamber exposing the resistor whereby either the said crushed carbon or the monolithic resistor may be intertubes, the latter passing through the said tiles and capable of being cooled by air or water.

This specificationsigned this 15th day of November, A. D., 1919.'

' JOHN THOMSON.

Witnesses:

J. R. AGNEW H, O. WEED.

so fiat cover for the furnace whereby the heat- 

